Beryllium-10, thorium-231 and protactinium-231 in galapagos Microplate Sedimentes: implications of hydrothermal activity and paleoproductivity changes during the last 100.000 years.

Frank, Martin, Eckardt, J. D., Eisenhauer, Anton , Kubik, P. W., Dittrich- Hannen, B., Segl, M. and Mangini, A. (1994) Beryllium-10, thorium-231 and protactinium-231 in galapagos Microplate Sedimentes: implications of hydrothermal activity and paleoproductivity changes during the last 100.000 years. Paleoceanography, 9 (4). pp. 559-578. DOI 10.1029/94PA01132.

[img]
Preview
Text
scan_2017-01-06_13-08-18r.1.pdf - Reprinted Version

Download (7Mb) | Preview

Supplementary data:

Abstract

Biogenic particle fluxes from highly productive surface waters, boundary scavenging, and hydrothermal activity are the main factors influencing the deposition of radionuclides in the area of the Galapagos microplate, eastern Equatorial Pacific. In order to evaluate the importance of these three processes throughout the last 100 kyr, concentrations of the radionuclides 10Be, 230Th, and 231Pa, and of Mn and Fe were measured at high resolution in sediment samples from two gravity cores KLH 068 and KLH 093. High biological productivity in the surface waters overlying the investigated area has led to 10Be and 231Pa fluxes exceeding production during at least the last 30 kyr and probably the last 100 kyr. However, during periods of high productivity at the up welling centers off Peru and extension of the equatorial high-productivity zone, a relative loss of 10Be and 231Pa may have occurred in these sediment cores because of boundary scavenging. The effects of hydrothermal activity were investigated by comparing the 230Thex concentrations to the Mn/Fe ratios and by comparing the fluxes of 230Th and 10Be which exceed production. The results suggest an enhanced hydrothermal influence during isotope stages 4 and 5 and to a lesser extent during isotope stage 1 in core KLH 093. During isotope stages 2 and 3, the hydrothermal supply of Mn was deposited elsewhere, probably because of changes in current regime or deep water oxygenation. A strong increase of the Mn/Fe ratio at the beginning of climatic stage 1 which is not accompanied by an increase of the 230Thex concentration is interpreted to be an effect of Mn remobilization and reprecipitation in the sediment.

Document Type: Article
Keywords: Beryllium-10, thorium-231, protactinium-231, Galapagos Microplate, Sediments, hydrothermal activity, paleoproductivity, the last 100.000 years
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1029/94PA01132
ISSN: 0883-8305
Date Deposited: 18 Feb 2008 17:27
Last Modified: 06 Jan 2017 12:37
URI: http://oceanrep.geomar.de/id/eprint/5090

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...